An EC 1.3.1.* (oxidoreductase acting on CH-CH group of donor, NAD+ or NADP+ as acceptor) inhibitor that interferes with the action of of 3-oxo-5alpha-steroid 4-dehydrogenase (NADP+), EC 1.3.1.22, the enzyme which converts testosterone (CHEBI:17347) into the more potent androgen 5alpha-dihydrotestosterone.